Filling The T-Rex Link: Newfound Tyrannosaurus Rex Fossils in Montana Can Solve the Evolution of the Species

LEWISTON, MONTANA- Since Tyrannosaurus rex is regarded as the "monarch" of the dinosaurs, the "tyrant lizard" only inhabited Earth for roughly the last 2 million years of the 150-million-year "Age of Dinosaurs." Scientists claim they have discovered a missing component of the tyrannosaur ancestry.

The newly discovered species might assist in settling a major controversy concerning T. rex's evolutionary heritage. Daspletosaurus wilsoni is a new species with an unusual arrangement of spiky hornlets surrounding its eyes. The tyrannosaur was identified using portions of a fossilized skull and skeletal elements from the Cretaceous era, including a rib and toe bone (145 million to 66 million years ago).

Based on recent research released on Nov. 25 in the journal Paleontology and Evolutionary Science, paleontologists from Badlands Dinosaur Museum in North Dakota discovered the fossils in the Judith River Formation in northeastern Montana between 2017 and 2021.

Finding The Missing Link: Locating The Fossils

The scientists determined the fossils when crewmember Jack Wilson observed a little, flat bit of bone protruding from the bottom of a mountainside, which subsequently revealed to be a portion of the dinosaur's snout. On the other hand, the bones proved extremely difficult to excavate due to their location being completely buried 26 feet (8 meters) of rock formation. Before they could start unearthing the individual bones, the researchers had to carefully chip away enormous sections of the cliff with jackhammers.

The fossil, labelled BDM 107, was jokingly dubbed "Sisyphus" because of the great effort necessary to remove the depositional environment. (Sisyphus is a Greek mythological person who, after avoiding death twice, was compelled by Hades, the god of the underworld, to roll a rock up a mountain for eternity.)

Scientists believe that D. wilsoni was a descendant of Daspletosaurus torosus and the ancestor of Daspletosaurus horneri, which lived approximately 77 and 75 million years ago. The anatomy of the newly discovered beast supports the theory that the Daspletosaurus branch is related to the powerful T. rex. Tyrannosauridae, which comprises nine genera, includes all three daspletosaur species. Daspletosaurus is the Greek term for "frightful lizard."

The Tyrannosauridae ancestry seems to have been difficult to untangle until recently, making it impossible to pinpoint the precise evolutionary connections between distinct species, as Live Science reported.

(Photo: © Rudolf Hima & Badlands Dinosaur Museum.)
The new specimen, "Sisyphus", is one of four tyrannosaur skeletons recently collected by Badlands Dinosaur Museum. Here the four tyrannosaurs dispute ownership of the fresh carcass of a Centrosaurus.

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Unlocking T-Rex Ancestry

Towards research co-authors and paleontologists Elas Warshaw and Denver Fowler, many scholars dispute if tyrannosaurids constitute a single lineage developing in situ or numerous species with close affinities that do not derive from one another. They stated that a scarcity of slightly elevated specimens to evaluate hasn't helped. However, the finding of D. wilsoni as the researchers believe that the three daspletosaurs evolved sequentially, like "continuous staircase levels in a distinct evolutionary divergence," rather than breaking each other off like "evolution relatives."

D. wilsoni is a suitable addition for a distinct form between D. torosus and D. horneri. Following the statement, it was named horneri because it exhibits various characteristics with some more prehistoric tyrannosaurs, such as possessing a pronounced set of horns all around the eye and characteristics present in newer species, such as expanding air pockets in the skull.

In this manner, the D. wilsoni represents a "halfway point" or "missing link" connecting younger and older tyrannosaur species. Given that these species might have evolved sequentially, the researchers believe that the remaining tyrannosaurids, including T. rex, may have appeared in the same linear method. The researchers believe they are organising a fresh study to investigate this notion.